Note: Descriptions are shown in the official language in which they were submitted.
L ~
Low Phos~horus Lubricants
The present invention relates to lubricating coMpositions,
e~pecially automobile crankcase lubricants, containing low or
zero amounts of phosphorus.
There is currently a drive to reduce the amounts of phosphorus
in lubricants because of the deleterious effect phosphorus has
on catalysts commonly used in catalytic converters used for
emission control. Levels of phosphorus have typically been of
the order of 0.1% but there is an increasing need ~o reduce
phosphorus levels to below 0.05 wt ~ or remove it altogether.
However; zinc dialkyl dithiophosphates (ZDDP) and other
phosphorus containing additives have been widely used as
anti-wear and/or anti-oxidant additives and simply reducing or
removing such components results in lubricants with poor engine
performance.
This invention provides lubricant compositions and concentrates
with low or zero phosphorus contents which comprise copper,
sulphur, and a bearing corrosion inhibitor, which compositions
have been found to have remarkable engine performance.
US-A-2356661 deals with lubricating oils containing 50 to lO00
parts per million of copper as an oil-soluble organic compound
such as copper dialkyl dithiocarbamates and including
phosphorus containiny compounds together with from 0.1 to 0.5
wt ~ of total sulphur in the oil, sulphur being provided as
oil-soluble organic sulphur compounds such as thiocarbamates.
US-A-2343756 discloses the addition of copper co~pounds
including phosphorus-containing copper complexes in conjunction
with sulphur compounds, to lubricating oils. Amounts of from
0.1 to 0.5 wt % of sulphur are disclosed, with amounts in
excess of 0.5 wt % sulphur described as being potentially
detrimental. In VS-A-2552580, cuprous thiophosphates are
included in lubricant compositions at relatively high levels,
which will give high phosphorus level in the oils.
,~
~3~
In US-A~3346493, a wide variety of metal-containing poly~eric
amine metal reactants are employed as detergents in lubricant
compositions. In an isolated example, a lubricant is described
containing inter alia, a copper salt of an acylated nitrogen
compound, 0.075% phosphorus as a ZDDP reacted with hexene
oxide, and a sulphurized methyl ester of a tall oil acid.
Other copper containing lubricants either contain more
phosphorus or no sulphur. US-A-4122033 discloses the entire
group of transition metal compounds as antioxidation
stabilizers in conjunction with amines, selenides, phosphines
or phosphites and may be used in various applications including
as additives for lubricants. None of the foregoing documents
describe fully formulated lubricant oils which would be
appropriate to meet the requirements for modern lubricants and
none specifically address the reduction of phosphorus levels
while maintaining performance in antiwear, antioxidation and
corrosion inhibition.
EP-A-24146 discloses lubricant compositions containing an
ashless dispersant and/or polymeric viscosity index improver
dispersant and copper which may be in the form of a
dithiocarbamate, but requires the presence of zinc and from
0.01 to 0.5 wt % phosphorus. Thiadiazole polysulphides are an
optional component.
US-A-4330420 describes oils with reduced phosphorus content
(but only to 0.05%P) using mixtures of dialkyldiphenylamine and
a sulphurized polyolefin to compensate for reduction in the
amount of ZDDP. There is no disclosure of the use of copper or
thiadiazole polysulphides.
EP-A-89844 describes reaction products of 4,4'-methylene
bis(2,6-di-t~butyl phenol) and tri-Sec-C4_12 alkyl orthoborate
and their use in lubricants to enable the amount of ZDDP to be
reduced to provide from 0.05 to 0.11 wt g P.
_ 3 ~ ~3~
US-A-4490265 describes lubricating oils comprising
boron-containing heterocyclic compounds which may be in the
form of a metal salt including a copper salt, thiadiazole
polysulphides, terephthalic acid and as an vxidation inhibitor
either a bis(dithiobenzil) metal derivative where the metal may
inter alia be copper or a sulphur-bridged, bis hindered
phenol. The desirability of reducing or eliminating phosphorus
is not disclosed and all the Examples of lubricants contain
0.05 wt% P. US-A-4623474 makes a similar disclosure.
VS-A-4627930 also describes boron-containing heterocyclic
compounds which may be in the form of a copper salt and may be
sulphurized. Thiadiazole polysulphides and copper carboxylates
are also disclosed. Although the boron containing heterocyclic
compounds are described as phosphorus-free, there is no
disclosure of a fully formulated oil containing less than 0.05
wt % P. US-A-4629580 contains a similar disclosure.
US-A-4629579 discloses boron and metal-boron derivatives for
use as extreme pressure, anti-wear and friction reducing
additives for lubricating oils, and compositions including one
containing no ZDDP, but there is no disclosure of a composition
containing low or zero amounts of phosphorus, with sulphur and
copper.
Lubricant compositions containing low, or zero amounts of
phosphorus, but no copper are described in WO-A-8604601,
WO-A-8604602 and WO-A-8606092.
The invention seeks to provide lubricants having antiwear,
corrosion inhibition and antioxidant performance appropriate to
modern oil requirements with reduced or zero amounts of
phosphorous and without the need for large amounts and/or
expensive forms of antioxidant.
The term ~Modern oil~ as used herein in relation to automobile
crankcase lubricants refers to oil which can meet the current
requirements for crankcase lubricants in the major industrial
countries. ~igh performance engines, increased lifetime
_ 4 _ ~3~
requirements resulting from longer periods between oil changes,
and higher opeeating temperatures all contribute to the
increased performance required from lubricants. This invention
is particularly concerned with automobile crankcase lubricants
which can meet and exceed the requirements for the SF API
Engine Service Category for service station oils and/or the
requirements for the CD API Engine Service Category for
Commercial Oils/Diesel Engines, established jointly by API, SAE
and ASTM.
In one aspect, this invention provides a lubricant composition
comprising a major a~ount of a lubricating oil/ 5 to 500 parts
per million by weight (ppm) of added copper present in
oil-soluble form, one or more added oil-soluble
sulphur-containing compounds such that the composition
preferably comprises from greater than 0.5 to 2.0 wt % of total
sulphur, more preferably 0.5 to 1.0 wt % of total sulphur and
an effective amount o~ a bearing corrosion inhibitor, the
composition containing less than 0.01 wt % phosphorus,
preferably being substantially phosphorus-free.
In particularly preferred embodiments of the invention, the
lubricant composition will also contain one or more ashless
dispersants and/or one or more viscosity index improver
dispersants and/or one or more overbased additives which
function as antacid and anti-rust agents, such as overbased
calcium or magnesium sulphonates or phenates.
The use of copper in the invention enables a low phosphorus oil
with performance meeting the re~uirements of modern oils to be
obtained economically and with good control of oxidation, which
in an automobile engine is catalysed by metal accumulated in
the oil by wear or corrosion, with iron being a particular
oxidation catalyst. At unduly low concentrations of copper,
the anti-oxidant effect may not be sufficient for some
applications. At unduly high concentrations, the ash level of
the oil will he increased and an increased tendancy to bearing
corrosion may be observed. The amount of added copper in the
compositions will generally be within the range of 10 to 400
ppm, typically 10 to 300 ppm, preferably 10 to 200 ppm, e.g. 60
to 200 ppm.
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The ability of the compositions of the invention comprising low
amounts of oil-soluble copper compounds and very low or zero
a~ounts of phosphorus to provide adequate antioxidant and
antiwear performance for the stringent requirements of modern
engine tests is surprising. Copper is known to act in many
situations as an oxidation promoter or catalyst, and closely
related metalsr such as cobalt and chromium, are not effective
lubricant anti-oxidants. EP-A-24146 teaches the presence of at
least 0.01 wt % of each of phosphorus and zinc.
It is also surprising that the copper compound functions
effectively in compositions which may contain zinc and other
metal compounds, such as calcium or magnesium overbased
additivesl which have an inherent pro-oxidant activity.
The copper compounds used as ar.ti-oxidants in this invention
may be chosen from those described in EP-A-24146 as suitable
for lubricants provided that the copper compounds are
substantially free of phosphorus.
Thus, the copper may be blended into the oil as the oil-soluble
copper salt of a synthetic or natural carboxylic acid.
Examples of suitable carboxylic acids include Clo to Clg fatty
acids such as stearic or palmitic acid, unsaturated acids such
as oleic acid, branched carboxylic acids such as naphthenic
acids of molecular weight fro~ 200 to 500, neodecanoic or
2-ethylhexanoic acid and alkyl or alkenyl substituted
dicarboxylic acids such as polyalkene substituted succinic
acids, e.g. octadecenyl succinic acids, dodecenyl succinic
acids and polyisobutenyl succinic acids.
The copper may be blended into the oil as oil-soluble copper
dithiocarbamates of the general formula (~R'NCSS~nCu~ where n
is 1 or 2 and R and R' are the same or different hydrocarbyl
radicals containing 1 to 18, preferably 2 to 12 carbon atoms
such as alkyl, alkenyl, aryl, aralkyl/ alkaryl and cycloalkyl
radicals. Other copper and sulphur containing compounds such
as copper mercaptides, disulphides and thioxanthates are
suitable for use in the invention. Copper sulphonates,
phenates, and acetylacetonates may also be used.
- 6 - ~3~$~
Alternatively the copper may be introduced in the oil in an
oi~ insoluble form provided that in the finished lubricant
composition the copper is in the form on an oil-soluble
compound. The term "added copper n is intended to exclude
copper present in the oil as a result of accumulation of copper
in the oil during use, e.g. by wear or corrosion of
copper--containing components.
The lubricant compositions of the invention contain an added
oil-soluble sulphur compound. one preferred class of such
sulphur compounds are the dithiocarbamates, preferably of the
formula: (RR'NCSS~n M, wherein R, R' and n are as defined
hereinbefore and M is a suitable metal such as zinc, molybdenum
or (as indicated above) copper or a optionally substituted
hydrocarbyl radical. Preferred dithiocarbamates are dialkyl
dithiocarbamates preferably containing 2 to 12 carbon atoms
such as diamyl dithiocarbamates. A particularly preferred
compound is zinc diamyl dithiocarbamate.
Sulphur may also be introduced as a mercaptide particularly the
mercaptides of aliphatic mercaptans (including copper
mercaptides as indicated above), sulphurized unsaturated
organic compownds including sulphurized olefins (e.g.
US-A-4119549, ~S-A-4-4119550, US-A-4:L91659 and US-A-4147640),
sulphurized Diels-Alder adducts (e.g. US-A~3632566,
US-A-3498915 and US-E-27331) and particularly sulphurized
unsaturated alcohols and esters such as sperm oil substitutes,
e.g. sperm oil, sulphides including di- and polysulphides,
thioethers, thiophenols/ thioxanthates ~including copper
thioxanthates as indicated above), sulphurized esters,
thioesters, thioamides, thia201es such as benzothiazoles and
particularly mercaptobenzothiazoles, and thiadiazoles.
Mineral lubricating oils contain sulphur, whereas synthetic
oils may be sulphur-free, so that the amount of sulphur added
as a sulphur-containing compound varies according to the
basestock and the sulphur contents of other components in the
lubricating composition, more preferably so as to give a
sulphur content of greater than 0.5 to 1~0 wt % total sulphur.
~ 7 ~ 13~7~
The lubricant compositions of the invention advantageously
contain from 0.5 to 0.7 wt % total s, and most preferably 0.1
to 0.5 wt % S as added oil-soluble sulphur-containing
compound. They also preferably contain 0.01 to 0.5 wt % zn,
more preferably 0.05 to 0.2 wt % zn. In a particularly
preferred aspect the compositions contain 0.5 to 3 wt % zinc
dithiocarbamate.
.
The bearing corrosion inhibitor is a corrosion inhibitor
effective at inhibiting corrosion effects on bearings such as
Cu/Pb bearings, where effects such as copper staining and high
weight loss can be encountered. Such additives have been found
to promote the antiwear performance of the oil. Preferred
bearing corrosion inhibitors are borate esters such as B(OR)3,
(RO)2B-O-B(OR)2, (ROBO)3 (RO)2BORlOB(OR)2 and mixtures (wherein
R is a substituted or unsubstituted alkyl, aryl or aralkyl
group or two groups R form a substituted or unsubstituted
alkylene group and Rl is a substituted or unsubstituted
alkylene group) and these materials may be derived, for
example, from alcohols such as alkoxyalkanols (both short chain
alkanols and longer chain alcohols as in US A-4440656) and
polyetheralkanols; mono-, di- and ~rihydroxy alkanols, e.g.
2-ethylhexanol, 2-ethylhexan-1, 3-diol, butane-1,2-diol
butane-1,3-diol, glycerol and the acyclic polyols of
US-A-2866811; hydroxy esters such as glyceryl mono-oleate
oxazolines derived for example from oleic acid and
tris(hydroxymethyl)-aminomethane; sulphur-containing alcohols
such as may be obtained by reacting epoxides with mercaptans
e.g. t-dodecyl-mercaptoethanol; amino alcohols such as
alkanolamines e.g. triethanolamine and tri-isopropanolamine,
hydroxyamines made by reacting a primary amine (e.g.
oleylamine) or secondary amine with ethylene or propylene oxide
and the compounds of US-A-4406802. Preferred alcohols are
2-methylpentan-1,3-diol, butane-1,2-diol, butane-1,3-diol and
similar 1,2 and 1,3 diols, and ethoxyethanol.
In a preferred aspect the invention contains from 0.01 to 10 wt
%, preferably 0.1 to 5 wt %, of a borate ester especially an
ester of an alkoxyalkanol or a polyetheralkanol, e.g. a
tris(ethoxyethyl) orthoborate ester or metaborate ester, or a
biborate of a diol such as butane-1,3-diol.
As an alternative, the bearing corrosion inhibitor is a
thiadiazole mercaptan, especially a thiadiazole polysulphide
containing from 5 to 50 caebon atoms, a derivative or polymer
thereof. Preferred materials are the 1,3,4 thiadiazole
polysulphides such as those described in US-A-2719125, 2719126
and 3087932. Especially preferred is the compound 2,5-bis
(t-octadithio)-1,3,4-thiadiazole commercially available as
Amoco 150 or 2,5-bis(nonyldithio)-1,3,4-thiadiazole avallable
as Amoco 158. Other similar materials also suitable are
described in US-A-3821236, 3904537, 4097387, 4107059, 4136043,
4188299 and 4193882. Derivatives of thiadiazole mercaptans may
be used such as esters, condensation products with halogenated
carboxylic acids, reaction products with aldehydes and amines,
alcohols or mercaptansl amine salts, dithiocarbamates, reaction
products with ashless dispersants (e.g. US-A-4140643 and
US-A-4136043) and reaction products with sulphur halides and
olefins.
These materials are preferably present in an amount of from
0.01 to 10 wt ~, more preferably 0.1 to 5O0 wt % of the
lubricant composition.
The lubricating compositions may comprise small amounts of
phosphorus, less than 0.01 wt %, preferably less than 0.005 wt
%7 but more preferably the lubricating compositions are
substantially free of phosphorus.
In a preferred aspect the lubricating composition further
comprises:
(A) from 1 to 10 wt % of an ashless dispersant compound which
i s :
an ashless nitrogen or ester containing dispersant
compound preferably selected from:
(i) oil soluble salts~ amides, imides, oxazolines and esters~
or mixtures thereof, of long chain hydrocarbon
substituted mono and dicarboxylic acids or their
anhydrides;
a~em~
6t~
- - 9
~ii) long chain aliphatic hydrocarbon having a polyamine
attached directly thereto; and
(iii) Mannich condensation products formed by condensing a
molar proportion of long chain hydrocarbon
substituted phenol with 1 to 2.5 moles of
formaldehyde and 0.5 to 2 moles of polyalkylene polyamine;
wherein said long chain hydrocarbon group is a polymer of
a Cz to C5 monoolefin, said polymer having a molecular
weight of 700 to 5000; and/or
(B) from 0.3 to 10 wt %, of a nitrogen or ester containing
polymeric viscosity index improver dispersant which may include
(a) polymers comprised of C4 to C24 unsaturated esters of
vinyl alcohol or C3 to Clo unsaturated mono- or
di-carboxylic acid with unsaturated nitrogen containing
monomers having 4 to 20 carbons;
(b) polymers of C2 to C20 olefin with unsaturated C3 to Clo
mono- or di-carboxylic acid neutralised with amine,
hydroxy amine or alcohols; and
(c) polymers of ethylene with a C3 to C20 olefin further
reacted either by grafting C~ to C20 unsaturated nitrogen
containing monomers thereon or by yrafting an unsaturatecl
acid onto the polymer backbone and then reactin~ said
carboxylic acid groups with amine, hydroxy amine or
alcohol.
The nitrogen containing dispersant additives are those known in
the art as sludge dispersants for crankcase motor oils, eOg.
such as shown in US-A-3275554, US-A-3565804, US-A-3442808,
US-A-3442808, GB-A-983040 or BE-A-658236.
The most commonly used dispersants are those formed by reacting
alkenyl succinic anhydride, e.g. polyisobutenyl succinic
anhydride, and an amine described in US-A-3202678, 3154560~
3172892, 3024195, 3024237, 3219666, 3216936 and BE-A-662875.
~L3~6~
Alternatively the ashless dispersants may he esters derived
from long chain hydrocarbon substituted carboxylic acids and
from hydroxy compounds such as monohydric and polyhydric
alcohols or aromatic compounds such as phenols and naphthols as
prepared for example in US-A-3522179.
Hydroxyamines which can be reacted with any of the aforesaid
long chain hydrocarbon substituted carboxylic acids to form
dispersants include 2-amino-1-butanol,
2-amino-2-methyl-1-propanol, p-(beta-hydroxyethyl)-aniline,
2-amino-1-propanol~ 3-amino-1-propanol, 2-amino 2-methyl-1
3-propane-diol, 2-amino-2-ethyl-1, 3-propanediol,
N-(beta-hydroxy-propyl)-N'-(beta-aminoethyl)-piperazine,
tris~hydroxmethyl) amino-methane (also known as
trismethylolaminomethane), 2-amino-1-butanol, ethanolamine,
beta-(beta-hydroxyethoxy)-ethylamine, and the like. Mixtures
of these or similar amines can also be employed.
Preerred dispersants are those derived from polyisobutenyl
succinic anhydride and polyethylene amines, e.q. tetraethylene
pentamine, polyoxyethylene and polyoxypropylene amines, e.g.
polyoxypropylene diamine, trisrnethylolamino~ethane and
pentaerythritol, and combinations thereof. One particularly
preferred dispersant combination involves a combination of (A)
polyiobutenyl succinic anhydride with (B) a hydroxy compound,
e.g. pentaerythritol, (C) a polyoxyalkylene polyamine, e.g.
polyoxypropylene diamine, and (D) a polyalkylene polyamine,
e.g. polyethylene diamine and tetraethylene pentamine using
about 0.01 to about 4 equivalents of (B) and (D) and about 0~01
to about 2 equivalents of (C) per equivalent of (A) as
described in US-A-3894763. Another preferred dispersant
combination involves the combination of (A) polyisobutenyl
succinic anhydride with (B) a polyalkylene polyamine, e.g~
tetraethylene pentamine, and (C) a polyhydric alcohol or
. ,, -,,: '' ,
3~6~
polyhydroxy-substituted aliphatic primary amine, e.g.
pentaerythritol or trismethylolaminomethane as described in
US-~-3632511.
The alkenyl succinic polyamine type dispersants can be further
modified with a boron compound such as boron oxide, boron
halides, boron acids and ester of boron acids in an amount to
provide 0.1 to 10 atomic proportions of boron per mole of the
acylated nitrogen compound as generally taught in US-A-3087936
and 3254025. Mixtures of dispersants can also be used such as
those described in US-A-4113639.
The oils may contain from 1.0 to 10 wt %, more preferably 2.0
to 7.0 wt % of these dispersants.
The dispersancy may be provided by 0.3 to 10% of a polymeric
Viscosity Index improver dispersant, for example copolymers of
alkyl methacrylates with N-vinyl pyrrolidone or
dimethylaminoalkyl methacrylate, alkyl fumarate-vinyl acetate
N-vinyl pyrolidine copolymers, post-grafted interpolymers of
ethylene-propylene with an active monomer such as maleic
anhydride which may be further reacted with an alcohol or an
alkylene polyamine, such as in US-A-4149984; or styrene/maleic
anhydride polymers post-reacted with alcohols and amines,
ethoxylated derivatives of acrylate polymers such as in
US-A-3702300.
Magnesium and/or calcium containing additives are frequently
included in lubricating compositions either alone or in
combination with other alkali metal or alkaline earth metal
additives such as those containing sodium. These may be
present for example as the metal salts of sulphonic acids/
alkyl phenols, sulphurised alkyl phenols, alkyl salicylates,
naphthenates, and oGher oil soluble mono- and di-carboxylic
acids.
- 12 ~ ~ ~'6~7~
Highly basic alkaline earth metal alkaryl sulfonates are
geneeally known for example in US-A-3150088 and 3150089. For
the purposes of this invention, a preferred alkaline earth
sulfonate is magnesiurn or calcium alkyl aromatic sulfonate
having a total base number (TBN, as measured by the procedure
of ASTM D2896) ranging from 300 to 400.
Polyvalent metal alkyl salicylate and naphthenate materials may
also be included, such as the methylene and sulfur bridged
materials which are readily derived from alkyl substituted
salicylic or naphthenic acids or mixtures of either or both
with alkyl substitu~ed phenols. Basic sulfurized salicylates
and a method for their preparation are shown in US-A 3595791.
The sulfurized metal phenates can be considered the ~metal salt
of a phenol sulfide~ which thus refers to a metal salt, whether
neutral or basic, of a compound typified by the general formula:
b~sx ~ sx ~ 1~
OH OH n OH
where x = 1 or 2, n = 0, 1 or 2
or a polymeric form of such a compound, where R is an alkyl
radical, n and x are each integers from 1 to 4, and the average
number of carbon atoms in all of the R groups is at least about
9 in order to ensure adequate solubility in oil. The
- 13 - ~ ~ ~67~
individual R groups may each contain frorn 5 to 40, preferably 8
to 20, carbon atoms. The metal salt is prepared by reacting an
alkyl phenol sulfide with a sufficient quantity o~ metal
containing material to impart the desired alkalinity to the
sulfurized metal phenate.
The sulfurized alkyl phenol is converted by reaction with a
metal containing material including oxides, hydroxides and
cornplexes in an amount su~icient to neutralize said phenol
and, if desired, to overbase the product to a desired
alkalinity by procedures well known in the art. Pre~erred is a
process of neutralization utilizing a solution of metal in a
glycol ether.
Magnesium and calcium containing additives such as described
above although beneficial in other respects can increase the
tendency o~ the lubricating oil to oxidise. This is especially
true of the highl~ basic sulphonates.
According to a preferred embodiment the invention therefore
provides a crankcase lubricating composition also containing
~rom 2 to 8000 parts per million of calcium and/or magnesium.
The magnesium and/or calcium is generally present as basic or
neutral detergents such as the sulphonates and phenates, and
preferred additives are basic magnesium or calcium
sulphonates. Preferably the oils contain from 500 to 5000
parts per million of calcium and/or magnesium ~rom such
additives.
These compositions of our invention may as an alternative or in
addition contain other similar metal-containing detergent
additives, for example, those containing barium, sodium,
potassium or lithium.
- 14 - ~3~
The lubricating oil used in the lubricant composition may be a
mineral lubricating oil or a synthetic lubricating oil or a
mixture thereof. Suitable synthetic oils include diester oils
such as di(2-ethyl-hexyl) sebacate, azelate and adipate;
complex ester oils such as those formed for dicarboxylic acids,
glycols and either monobasic acids or monohydric alcohols;
silicone oils; sulfide esters; organic carbonates; hydrocarbon
oils and other synthetic oils known to the art. The invention
is particularly useful in mineral lubricating oils and has the
added benefit that it may allow use of base stock oils that
have inferior antioxidant properties to those currently used.
The lubricating compositions of the present invention may and
usually will contain other traditional lubricant additives
provided that they are substantially phosphorus-free - for
example, rust inhibitors such as oleic acid and its
derivatives, such as N-oleylsarcosine, and oleic acid dimers,
and trimers, lecithin~ sorbitan mono-oleate, dodecyl succinic
anhydride or ethoxylated alkyl phenols; pour point depressants
such as copolymers of vinyl acetate with fumaric acid esters of
coconut oil alcohols; and viscosity index improvers such as
olefin copolymers or polymethacrylates.
In copper-free oils other antioxidants in addition to the zinc
dialkyldithiophosphate are sometimes required to improve the
oxidative stability of the oil. These supplementary
antioxidants are included especially when the basestock has
poor oxidative stability; and typically the supplementary
antioxidant is added to the oil in amounts from 0.1-1~5 wt %.
The supplementary antioxidants that are used include phenols,
hindered-phenols, bis-phenols, and sulphurised phenols,
catechol, alkylated catechols and sulphurised alkyl catechols,
diphenylamine and alkyl diphenylamines and
phenyl-l-naphthylamine and its alkylated derivatives.
- 15 - ~3~
The inclusion of small amounts of copper generally removes the
need for these supplementary antioxidants. It would, however,
still be within the scope of our invention for a supplementary
antioxldant to be included especially for oils operating under
particularly severe conditions where the presence of such
supplementary antioxidants may be beneficial, provided that
substantially no phosphorus is thereby introduced.
Additives for lubricating oils are generally supplied as
concentrates in oil for incorporation into the bulk lubricant.
The present invention therefore provides concentrates
comprising an oil solution containing:
(1) less than 0.1 wt % of phosphorus;
~2) from 1 to 50 wt % of an oil-soluble sulphur-containing
compound;
(3) from 0.005 to 2 wt % of copper; and
(4) from 0.1 to 20 wt % of a bearing corrosion inhibitor,
and optionally
~5) a dispersant selected from the group consisting o:
(a) 0 to 6G, e.g. 10 to 60 wt ~ of an ashless
dispersant compound,
(b) 0 to 40, e.g. 3 to 40~ of a polymeric viscosity
index improver dispersant, although it is usual to
add any viscosity index improver separately.
The concentrate may also contain other additives such as the
deteryents and viscosity index improvers previously described.
A particularly preferred concentrate also contains a magnesium
and/or calcium containing additive and the invention therefore
provides a concentrate which further comprises from 0.01 to 8
wt ~ of calcium and/or magnesium.
:~3~
The following Examples are now given, though only by way of
illustration, to show certain aspects of the invention in more
detail.
Comparative Examples I-VI and ~xamples 1 4
In the following Comparative Examples and Examples of the
invention, formulations are prepared with the combinations and
amounts of additives set out in Table 1, with the balance being
a diluent oil suitable for lubricating compositions and
comprising 0.3 wt ~ sulphur. The additives used are as follows:
A is a dispersant Y.I. additive comprising an oil
solution containing 21% of a multifunctional
ethylene-propylene copolymer and containiny 0.29 wt % N.
B is an ashless dispersant comprising a 50 wt % oil
solution of borated polyisobutenyl succinimide having a
polyisobutenyl radical with a molecular weight of
approximately 950 and containing 1.6 wt ~ N and 0.35 wt %
B.
C is an oil solution of an overbased magnesium sulphonate
having a TBN of 400 and a magnesium content of 9.2 wt
and a sulphur content of 1.7 wt %.
D is an oil solution of an overbased calcium sulphonate
having a TBN of 300 and a calcium content of 11.9 wt %
and a sulphur content of 1.9 wt %o
~ is an oil solution of copper oleate containing 4 wt
copper.
F is a 30 wt % solution in oil of a hindered methylene
bis-phenol antioxidant.
- 17 - ~3~6~
G is an alkylated diphenylamine antioxidant, commercially
available as Irganox L-57 fro~ Ciba-Geigy.
H is a 50 wt % oil solution of a zinc diamyl
dithiocarbamate containing 6 wt % of zinc and 12 wt %
sulphur.
J is an orthoborate ester made from ethoxyethanol
comprising 5 wt ~ of boron.
K is 2,5-bis(nonyldithio)-1,3,4-thiadiazole, co~mercially
available as Amoco 158 from Amoco Chemical Company,
comprising 33 wt % sulphur.
L is an oil solution containing 12 wt % of molybdenum as
the octoate.
M is a sulphurized ester sperm oil substitute,
commercially available as Emery 9844 from Emery
Corporation, and comprising 11.5 wt % sulphur.
The formulations were tested in the following standard tests:
Seq. IIID engine test according to ASTM STP 315M Part II
in which the maximum and average cam plus lifter wear are
measured. A pass in this test is achieved with maximum
wear of 0.02 cm tO.008 in.) or better, and an average
wear of 0.01 cm (0.004 in.) or better.
Kinematic viscosity increase in the Seq. III~ was
measured at 40~C as a percentage increase in 64 hours. A
pass is achieved in this test by achievinq a viscosity
increase in 64 hours of not more than 375%.
CRC-L-38 Screener engine test based on ASTM STP 509A PE
IV in which the bearing weight loss (BWL) is measured~ A
pass in this test is achieved with BWL of not more than
40 mg
Tf~deinar~
- 18 - ~3~7'~
-
The results are shown in Table 2. These results show the
invention provides a surprising advantage in lubricants which
have excellent antioxidant, anti-wear, and bearing corrosion
inhibition with substantial absence of phosphor~s. Comparative
Examples I, II and III show that in the absence of a bearing
corrosion inhibitor, wear performance was inadequate.
Comparative Example IV shows that the addition ~f a molybdenum
additive did not improve wear performance. Comparative Example
V shows that in the absence of copper antioxidant performance
was inadequate even with conventional amounts of other known
antioxidants.
A comparision of Comparative Example V with Example 2 shows
that the use of copper not only improves antioxidant
performance but also surprisingly improves antiwear
performance. The Examples of the invention show that the
performance of the formulations is not merely summation of the
performance of individual additives, but gives a surprising
improvement in antiwear, antioxidant and bearing corrosion
performance, while having phosphorus levels below those
commercially employed in conventional oils.
~ 3 ~ 6' 7 ~
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- 21
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Comparative Examples VIIX - IX and Examples 5 -_7
A key factor in the performance of crankcase lubricating
oils in modern engines is their resistance to oxidation,
particularly the avoidance of excessive viscosity
increase~ The effectiveness of the compositions of the
invention in resisting viscosity increase is demons~rated
in the Seq~ IIID engine tests demonstrated in Examples 1-4
above. A further de~onstration is given below in a bench
test - the ERCOT test - designed to simulate the
oxidative, iron-catalysed environment of an internal
combustion engine.
In the ERCOT test reported below a 300 gm sample of the
oil composition under test containing 40 ppm of iron as
ferric acetylacetonate was oxidised by passing 1.7 l/min
o~ air through the sample at 165C and the viscosity was
determined at intervals up to 64 hours using a Hakke
viscometer. The results are expressed in centipoise (cp).
Comparative Examples VII - IX follow Example 11 oE
WO-A-8604601, Example 13 of WO-A~8604602 and Example XI of
WO-A-06092 but using similar materials selected from those
identified by letter in these Examples. The Comparative
Examples do not use copper, and the results in Table 3
below show inadequate control of viscosity, whereas the
compositions of the invention in Examples S-7 de~onstrate
the effectiveness of the invention for use in modern oils
exposed to an oxidative environment over a long period
with extended engine oil drain times.
Apart from the components identified hereinbefore, the
following were used:-
N is a dispersant similar to dispersant B, but wherein thepolyisobutenyl radical has a molecular weight of
approximately 1300, and the dispersant contains 1.46 wt %
N and 0.32 wt ~ B.
P is an anti-wear additive comprising an oil solution (90
active ingredient3 of a diisooctyl 2inc dithiophosphate
which contains 7.0 wt % P and 7.7 wt % Zn.
- - 22 -
TABLE~ 3
_._ .
Example VII VIII IX 5 6 7
. . ~
Component (%)
H 2.0 2.0 - - 1.5
M 2.0 2.0 2.0 1.0 - 1.0
N 4.1 4.1 4.1 4.1 4.1 4.1
C 1.5 1.5 1.5 1.5 1.5 1.5
K 0.1 - - - 0.5 0.5
J - - 2.0 1.0
O . 1
E - - - 0.4 0.4 0.4
Oil To 100% -- ------------------~---------~
- -- - - - _ .. _ _,
Visc. (cp) at EIours
38.2 38.9 36.635.6 36.9 3~.9
~6 95.6 100.~ ~300 38.9 56.1 77.8
24 266.7 293.2 40.8 79.4137.7
~300 ~300 70.3170.4214.2
4~ 135.818~.9221.6
64 260.8218.4262.4
.
;~3~6~
-~ - 23 -
Concentrates - Typical concentrates for providing the
above formulations,
~t % %S ~Cu %B
B 33.7 0.12
C1~3 o O i) ~ 31
E 3~4 0~16
J 11.2 . 0.56
M 33~? 3~38
100.0 4.19 0.16 0.68
: Example 4 B 35.7
C 19.1 0.32 0.13
E 3.6 0.14
K 5.9 1.95
M 35.6 4.09
_
100 6.36 0~14 0~13
Concentrates may also contain some diluent oil to improve
handling (reduce viscosity).
